Travis Huxman, a UC Irvine ecology and evolutionary biology professor, downloads data from a station that measures the depth profile of soil moisture from sensors in the ground.

Travis Huxman, a UC Irvine ecology and evolutionary biology professor is shown near the 63-acre site at Loma Ridge, near Irvine Regional Park. The site is Orange County's most expansive experiment in habitat conservation.

Sarah Kimball, program coordinator for the center for environmental biology at UCI, cuts leaf clippings to measure their water content.

Sarah Kimball examines a leaf in a pressure chamber. The chamber squeezes the leaf at high pressure so they can determine with precision how much water is inside the leaf.

A high pressure chamber is used to determine with precision how much water is inside the leaf.

The 63-acre site at Loma Ridge, near Irvine Regional Park is Orange County's most expansive experiment in habitat conservation. “This is enormous,” professor Travis Huxman said. “You can see banding and rows; that's because it's all set up like a giant experiment.”

The question for Orange County’s environmental future is simple: How do you preserve a suite of native plants and animals, on lands interlaced like fingers with urban development, for generations to come?

The answer, according to a group of grass-stained scientists: by putting evolution to work.

Orange County is in the middle of a years-long experiment with its wildlife and wild places. It began 17 years ago with the creation of the Nature Reserve of Orange County, 37,000 acres of wildland across the county’s midsection managed under a single umbrella of protection.

Part of the job of preserving the county’s native plants and animals, some threatened or endangered, some not, was handed to scientists.

Now ecological specialists from UC Irvine and Chapman University are taking the scientific investigation of the county’s wild plants and animals to a whole new level.

TRACKING EVOLUTION

They are unraveling the evolutionary relationships among the herbs, shrubs and grasses native to Orange County to use them as a weapon against invaders – non-native plants, such as mustard or artichoke thistle, that can displace or even wipe out native ecosystems.

“One problem is the problem of species invasions into these restoring habitats,” says Travis Huxman, a UC Irvine ecology and evolutionary biology professor. “So one thing we’d like to do is put together combinations of native species to occupy all the niches to prevent an invader from moving in.”

But weaving the fabric of an ecosystem so tightly that it excludes invaders requires an intimate knowledge of the plants’ evolutionary traits, as well as their evolutionary history with one another.

That is where Jennifer Funk comes in.

The Chapman University assistant professor is well known among conservation scientists for a paper she published in 2008.

“It was a theoretical paper,” she said. “Theory suggests we should be able to build native plant communities that will resist exotic species invasion – if we understand how they’re using water, light and nutrients.”

Her work has been cited by other scientists, but now she is trying to test it in the field – literally.

Last week, she and Sarah Kimball of UC Irvine were clipping leaves of native plants at the “seed farm,” an expanse of land operated by the Irvine Ranch Conservancy.

FARMING NATIVE PLANTS

The conservancy grows a variety of native plants on the seed farm to be used to restore native habitat in places where it has been stripped away, or overwhelmed by non-native species.

Kimball and Funk were placing their clippings inside pressure chambers; by squeezing them at high pressure, the scientists can determine with precision how much water is inside the leaf.

Water is a critical factor in understanding the evolutionary traits of plants. The measurements were part of Funk’s years-long effort to try to validate her theory about plant communities that resist invasion.

“My results are sort of mixed,” she said. “It seems like it can work in some systems, but it depends on what traits you’re looking at.”

But to create invasion-proof restoration plots, the scientists also need to know how the various plants in Orange County’s native ecosystems, primarily a plant community called coastal sage scrub, evolved together.

Cue Kimball.

“I’m interested in thinking about how these species came to coexist through evolutionary time,” she said. “And when we’re trying to create a new community through restorations, what is the best way to do that?”

The scientists’ cooperative effort does not recognize traditional boundaries between pure research on the one hand and conservation on the other.

Instead, they take their discoveries directly to the realm of wildland management, pursuing both scientific knowledge and habitat conservation at the same time.

“This is a very unusual thing to find,” said Jutta Burger, co-director of science and stewardship at the Irvine Ranch Conservancy. “And it’s mostly because the academic world and the applied world are so disconnected. Normally, the two circles don’t really have any common area to meet and communicate.”

After checking in with Kimball and Funk, the next stop for Huxman, who is the director of UC Irvine’s Center for Environmental Biology, involved driving to the sloping and plunging hillsides of Orange County’s Loma Ridge.

THE BIG EXPERIMENT

Near Irvine Regional Park, the 63-acre site is perhaps Orange County’s most expansive experiment in habitat conservation.

“This is enormous,” Huxman said as he pulled into the site to download water-use data from sensors embedded in the soil. “You can see banding and rows; that’s because it’s all set up like a giant experiment.”

Strips of native plants, in varying combinations, are grown alongside invaders like wild mustard; the scientists monitor how well some strips fare compared with others.

The plant combinations might behave differently, for instance, across cycles of wet and dry years.

“The right community in one year might be different if it’s a drought year,” he said.

And the scientists are monitoring far more than how the plants cope with invaders.

“There’s lots of metrics to think about,” Huxman says. “How much soil stays on the hill, or slope, because these degraded lands are losing soil like mad; whether the streams actually flow in these watersheds; how resilient they are following fire. There are all kinds of these questions to layer on top of it.”

Huxman and his team work routinely with the Nature Reserve of Orange County, which conducts a variety of scientific initiatives to try to keep the reserve intact and healthy.

The reserve’s executive director, Jim Sulentich, said Huxman’s group brings careful thought and analysis about “a reserve system smack dab in the middle of a rather complicated human environment.”

Working with land managers such as the Nature Reserve and the Irvine Ranch Conservancy, as well as top researchers, allows Huxman to mix sophisticated theory with hands-on habitat restoration.

It’s a blend he says could offer a model for how to conduct scientific investigations and restore native landscapes at the same time.

“We like to think that the planned growth, the way this region has grown and thought about growth, is forward thinking,” he said. “And this is a forward-thinking way of doing natural resource management. So there will be different kinds of learning curves. That’s what makes it exciting.”

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